code: def test_common_type_empty(self, xp):
      ret = xp.common_type()
      assert type(ret) == type
      return ret
  
file_path: cupy/tests/cupy_tests/test_type_routines.py
imports: import unittest
  import numpy
  import pytest
  import cupy
  from cupy import testing
label_desc: Use image node_id 1 for calling the TestCommonType obj's underlying member method code with example usage: obj.test_common_type_empty(xp) and returns: ret